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Rectorseal 83560 Hot Block - Reusable Heat Absorption Putty

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SKU 83560

Rectorseal 83560 Hot Block - Reusable Heat Absorption Putty

Hot Block is a pliable, formable putty-textured packing for protecting nearby HVAC/R and plumbing pipe, valves, components and surfaces from damaging heat conduction, transfer and sparks during jobsite brazing, soldering and welding for commercial refrigeration, air conditioning and plumbing systems. While many heat blocking putties are one-time use, Hot Block is reusable dozens of times, because its proprietary formulation is easily rejuvenated with a spritz of water before storing back into its 8-ounce (metric) plastic jar.

Hot Block separates surrounding areas from potentially conductive brazing/soldering temperatures of 850°F (454°C) and reduces them by up to 90 percent.  It also doesn’t degrade from welding temperatures of up to 3,000°F (1,649°C). Besides absorbing heat, Hot Block can also prevent nearby drywall or wood from igniting, existing fitting joints from unsoldering, or flange bolt/nut threads, valves and sensitive equipment from residual spark damage.

It is available in 8-ounce (0.2-liter) plastic jars from HVAC and plumbing wholesale distributors. The jar includes a four-color label with instructions.


  • Reusable for life
  • Blocks direct and conductive heat
  • Stops the transfer of heat up to 3000°F (1650°C)
  • Non-Toxic
  • Non-Flammable
  • Odor free
  • Biodegradable
  • Can be used as a jigging tool
  • Stops warpage on thin metal


  • Block direct and conductive heat transfer on any surface or metals when brazing, soldering or welding
  • Protect heat sensitive parts and eliminate discoloration, warpage and distortion
  • Hold, align and jig parts for brazing, soldering or welding
  • Works as a heat shield when protecting valves and fittings
  • Effective while using MAPP gas, Oxy-Acetylene, MIG, TIG, Arc and propane torches


  • All types of surfaces and metals, including joints, valves, fittings, composite panels, copper, brass, rubber and plastics